isofs: validate block number from NFS file handle in isofs_export_iget

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Summary

CVECVE-2026-46124
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-28 10:16:27 UTC
Updated2026-05-30 11:17:22 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: isofs: validate block number from NFS file handle in isofs_export_iget isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker- controlled block number (ifid->block or ifid->parent_block) from the NFS file handle to isofs_export_iget(), which only rejects block == 0 before calling isofs_iget() and ultimately sb_bread(). A crafted file handle with fh_len sufficient to pass the check added by commit 0405d4b63d08 ("isofs: Prevent the use of too small fid") can still drive the server to read any in-range block on the backing device as if it were an iso_directory_record. That earlier fix was assigned CVE-2025-37780. sb_bread() on an out-of-range block returns NULL cleanly via the EIO path, so there is no memory-safety violation. For in-range reads of adjacent-partition data on the same block device, the unrelated bytes end up in iso_inode_info fields that reach the NFS client as dentry metadata. The deployment surface (isofs exported over NFS from loop-mounted images) is narrow and requires an authenticated NFS peer, but the malformed-file-handle class is reportable as hardening next to the existing CVE-2025-37780 fix. Reject block >= ISOFS_SB(sb)->s_nzones in isofs_export_iget() so the check covers both isofs_fh_to_dentry() and isofs_fh_to_parent() call sites with a single line.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS: 0.000180000 probability, percentile 0.051640000 (date 2026-05-29)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 952e7a7e317f126d0a2b879fc531b716932d5ffa bb0988ed4f2e26d59bbb58f644cb3a55b7521e21 git Not specified
CNA Linux Linux affected 56dfffea9fd3be0b3795a9ca6401e133a8427e0b 0a1af74ae2177bda3aee0837a0546309aa539d0d git Not specified
CNA Linux Linux affected 0405d4b63d082861f4eaff9d39c78ee9dc34f845 afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b git Not specified
CNA Linux Linux affected 0405d4b63d082861f4eaff9d39c78ee9dc34f845 4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6 git Not specified
CNA Linux Linux affected 0405d4b63d082861f4eaff9d39c78ee9dc34f845 24376458138387fb251e782e624c7776e9826796 git Not specified
CNA Linux Linux affected ee01a309ebf598be1ff8174901ed6e91619f1749 git Not specified
CNA Linux Linux affected 5e7de55602c61c8ff28db075cc49c8dd6989d7e0 git Not specified
CNA Linux Linux affected 63d5a3e207bf315a32c7d16de6c89753a759f95a git Not specified
CNA Linux Linux affected 0fdafdaef796816a9ed0fd7ac812932d569d9beb git Not specified
CNA Linux Linux affected 007124c896e7d4614ac1f6bd4dedb975c35a2a8e git Not specified
CNA Linux Linux affected 6.6.88 6.6.140 semver Not specified
CNA Linux Linux affected 6.12.25 6.12.88 semver Not specified
CNA Linux Linux affected 5.4.293 5.5 semver Not specified
CNA Linux Linux affected 5.10.237 5.11 semver Not specified
CNA Linux Linux affected 5.15.181 5.16 semver Not specified
CNA Linux Linux affected 6.1.135 6.2 semver Not specified
CNA Linux Linux affected 6.14.4 6.15 semver Not specified
CNA Linux Linux affected 6.15 Not specified
CNA Linux Linux unaffected 6.15 semver Not specified
CNA Linux Linux unaffected 6.6.140 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.88 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.30 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.7 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/24376458138387fb251e782e624c7776e9826796 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bb0988ed4f2e26d59bbb58f644cb3a55b7521e21 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0a1af74ae2177bda3aee0837a0546309aa539d0d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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